Philips Pus 436401/12 flashing backlights question

[nomoresonys]

Re: Philips Pus 436401/12 flashing backlights question

You solved it, good to hear. Lots of people work hard here trying to help people, so hopefully it isn't asking TOO much, to get an update, doesn't really matter to me but I do consider it very bad manners to just quit responding in the middle. I always just assume they wandered into the Bermuda Triangle or Quicksand or got hit by a bus etc, etc...

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

In answer to the last post on here yes i did give up or rather put it to bed for a while. But i will now tell what the outcome was or what i discovered was that my tv which was an auction site cheap buy and had been repaired before and fitted with a replacement power board which was not the correct one for my tv.
It should have been a philips 715G-7350 but was instead a 715G-6973 which is known to have the problem when backlights are changed.

The tv worked fine for around a year or more till the problem occured and only when an exact same model came up on an well known auction site and i won it with the intention of salvaging 2 tvs into one that i discovered the dicrepancy.

So i now have a functioning tv simply by having the correct power board in.

so anyone with the same problem check which power board you have and best of luck trying to find a 715G 7350 as they seem to be like gold dust.

post concluded unlike a lot of others on here. many thanks for peoples input.

[nomoresonys]

Re: Philips Pus 436401/12 flashing backlights question

So we're left to speculate that, the 2 ics fixed it or he fixed it another way or he gave up???

[nomoresonys]

Re: Philips Pus 436401/12 flashing backlights question

quite agree that just about everything {tv wise} on the forum originates from china i will order and get back to you when they arrive and fitted .

5 months? must be the slowest boat from china ever, or maybe he's just too busy to bother reporting back.

[betmen]

Re: Philips Pus 436401/12 flashing backlights question

quite agree that just about everything {tv wise} on the forum originates from china i will order and get back to you when they arrive and fitted .

Did you changed TPV101D chips and did you repair backlight?
I have similar problem with my tv...

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

quite agree that just about everything {tv wise} on the forum originates from china i will order and get back to you when they arrive and fitted .

[Diah]

Re: Philips Pus 436401/12 flashing backlights question

hi Been away for a couple of days so only just read the post .
Unfortunately tpv101D is only available from china and have had bad experience of fake items from china. Is there a better alternative to that chip with same/ better specifications available from UK supplier.

they are made in china.. UK / EU/ USA didn't make them.. and they are not a complex IC. so don't hesitated to place order from uncle XIN

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

hi Been away for a couple of days so only just read the post .
Unfortunately tpv101D is only available from china and have had bad experience of fake items from china. Is there a better alternative to that chip with same/ better specifications available from UK supplier.

[Diah]

Re: Philips Pus 436401/12 flashing backlights question

TPV101AD the way they are warm and the effect of heating left on print boards.. time to replace them both with out thinking twice.

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

thanks all leds are brand new and they test good with an led tester. Check continuity on the wiring and checked ok i will check the caps you mentioned and possibly swap them out as i have a scrap G7350 board with very similar set up which strangely enough does not have the 2 low ohm resistors just a jumper in place.

[nomoresonys]

Re: Philips Pus 436401/12 flashing backlights question

Wonder if caps c8624 and or c8627 might be a little weak, maybe double check that all the backlight connections are solid, did you use a backlight tester or test each led?

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

Just a quick update i flipped the board over with the intention of testing volts on the Ics and decided to try the freeze test and see if any component warmed quicker than the other . After switch on i normally get 15 seconds before the LEDs flash on and off but it was around 2 minutes before the on/off sequence started and only the 2 tpv101s got warmer quicker than anything else. Vcc was 12v and dim was 3.3v constant. Ill do more testing tonight when i get home.

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

great thanks for that

[Diah]

Re: Philips Pus 436401/12 flashing backlights question

the heat sinks do seem to get quite hot and i cannot find a data sheet for the TPV101AD chip. Ill test the diode mentioned and try to see if i can make sense of the IC readings.

this is service manual for yours BL circuit which it used by sharp too.. you can check TPV101AD

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

Yes i did remove one of the small SMD resistor on both ICs to slightly limit the current flow ,my thinking was the new leds may be rated different but did not make any difference so i haven't replaced it as yet .I am thinking along the lines as you, open circuit on the LED- which gives me the voltage fluctuation mentioned in post 1 the heat sinks do seem to get quite hot and i cannot find a data sheet for the TPV101AD chip. Ill test the diode mentioned and try to see if i can make sense of the IC readings.

[Diah]

Re: Philips Pus 436401/12 flashing backlights question

thanks for the photos.. did you remove one syns R on the LED- circuit or it was so..
you have open circuit at LED- so no booster enough they used 2 in one. i would start to test out side the boards beginning from D8104 /5 and the 2 8pin soc chips.. the load heating lasting on them are so much that they could be cut out one of there pins..

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

Here's a couple of photos full board and led driver section. I have been round with the soldering iron touching up a few joints but found nothing suspicious.
I did change u8106 with a one from another Philips board but made no difference.

[Diah]

Re: Philips Pus 436401/12 flashing backlights question

44V this is voltage but how about the currents.. here you have lack with it so couldn't support all 5 strips. do you have the S,M of the PCB ? if not upload closed photo of back side of this photo part to follow up the chart-

[KevM]

Re: Philips Pus 436401/12 flashing backlights question

Yes i still have the old strips but they don't have a protection Zener diode on them .
I take it you mean something like in the photo i attached of some Samsung strips. I have only ever come across a Toshiba set that had a shorted diode on the strip
Manual states a boost voltage of 48v for this power supply but i have only ever got 44v
when i switch on and stays steady.
Could one of the TPV101D ICs be faulty and breaking down so only one is taking most of the current and going into shutdown ?

[Diah]

Re: Philips Pus 436401/12 flashing backlights question

i have enclosed pic of rear of circuit board and connector.
please let me know if this is what you want to see.
I understand the part about 2 channels of supply to the connector.

sorry i was wrong because the print chart of the BL socket on top side absolutely wrong ,, and you have just One channel as LED+ pin 1.2 are connected to LED+ 11.12 and all LED- are one pin connection too.

you said the measurements on LED+ was 44.V. so do you still have the Old original strips. to test one LED only if it had or not zener diode built in at reserve probe. ?